Refractive unit

Refractive unit – This clinic is concerned with the correction of refractive errors using multiple different solutions to meet the needs and nature of each patient, and one of the most important solutions is the surgical correction options, which are a wide range of surgical procedures that suits every patient such as:

•  LASIK surgery
•  Femto LASIK
•  Implanting a second intraocular lens in front of the natural clear one which is called Phakic IOL (ICL, Verisyse IOL, .etc..)
•  And refractive clear lens exchange
•  Intra-corneal ring (Intacs) 
•  Photorefractive keratectomy
  

The refractive index of a medium is the ratio of the speed of light in a vacuum to the speed of light in the medium. It has no units, therefore. This is true also in the context of surface plasmon resonance. RIU is sometimes used to distinguish a number as referring to a refractive index. It also is useful for expressing quantities that vary with the refractive index. For instance, you might want to express the change in the scattering cross-section of a small dielectric particle due to changes in its refractive index. In that case, the appropriate units are m^2/RIU.